def global_collocations_rejoin():
print 'Global re-population...'
# add existing if do not exist yet
for article in cls.objects.filter(cluster_id=cluster_id):
index = json.loads(article.index)
for colloc in all_collocs.intersection(index.keys()):
# get or create because we are not filtrating old ones
TestCollocations.objects.get_or_create(ngram=colloc,
article=article,
defaults={'count': index[colloc]})
# we could screw up counts completely, need to update them
print 'Starting updates...'
from axel.libs.utils import print_progress
from axel.libs.nlp import _update_ngram_counts
for article in print_progress(cls.objects.filter(cluster_id=cluster_id)):
ngrams = sorted(article.testcollocations_set.values_list('ngram', 'count'),
key=lambda x: (x[1], x[0]))
if not ngrams:
continue
index = json.loads(article.index)
new_ngrams = nlp._generate_possible_ngrams([tuple(c.split()) for c in zip(*ngrams)[0]],
index)
new_ngrams = _update_ngram_counts(new_ngrams, index)
new_ngrams = sorted(new_ngrams.items(), key=lambda x: (x[1], x[0]))
new_ngrams = [k for k in new_ngrams if k[1] > 0]
if new_ngrams != ngrams:
obsolete_ngrams = set(ngrams).difference(new_ngrams)
article.testcollocations_set.filter(ngram__in=zip(*obsolete_ngrams)[0]) \
.delete()
for ngram, score in set(new_ngrams).difference(ngrams):
TestCollocations.objects.create(ngram=ngram, count=score, article=article)
def collocations(text, index, measures):
"""
Extract collocations from n-gram index
:type index: dict
:rtype list
"""
def filter_punkt(word):
return _PUNKT_RE.match(word)
def filter_len(word):
return len(word) < 3 and not word.isupper()
# do filtration by frequency > 2
bigram_index = dict([(tuple(k.split()), v) for k, v in index.iteritems()
if len(k.split()) == 2 and v > 2])
# Get abstract finder because we already have index
finder = nltk.collocations.AbstractCollocationFinder(None, bigram_index)
# remove collocation from 2 equal words
finder.apply_ngram_filter(lambda x, y: x == y)
# remove weird collocations
finder.apply_ngram_filter(lambda x, y: nlp._DIGIT_RE.match(x) and nlp._DIGIT_RE.match(y))
# remove punctuation, len and stopwords
finder.apply_word_filter(filter_punkt)
finder.apply_word_filter(filter_len)
finder.apply_word_filter(lambda w: w in nlp._STOPWORDS)
# build word distribution
from nltk.probability import FreqDist
word_fd = FreqDist()
for word in text.split():
word_fd.inc(word)
finder_big = nltk.collocations.BigramCollocationFinder(word_fd, finder.ngram_fd)
filtered_collocs = _update_ngram_counts(_generate_possible_ngrams(finder.ngram_fd, index),
index).items()
filtered_collocs.sort(key=lambda col: col[1], reverse=True)
# do not keep zero scores to exclude them in other rankings
filtered_collocs = [col for col, score in filtered_collocs if score > 0]
yield 'raw', filtered_collocs
# build bigram correspondence dict
corr_dict = defaultdict(list)
for ngram in filtered_collocs:
for bigram in nltk.ngrams(ngram.split(), 2):
corr_dict[bigram].append(ngram)
for measure_name, measure_func in measures:
bigrams = finder_big.score_ngrams(measure_func)
scored_ngrams = defaultdict(lambda: 0)
for bigram, score in bigrams:
for ngram in corr_dict[bigram]:
if scored_ngrams[ngram] < score:
scored_ngrams[ngram] = score
scored_ngrams = scored_ngrams.items()
scored_ngrams.sort(key=lambda col: col[1], reverse=True)
yield measure_name, zip(*scored_ngrams)[0]
